Certain foods, and particularly meat products such as ground beef and other comminuted food substances, are commonly packaged in what are called chub packages. These packages are generally produced at central processing plants operated by supermarket chains or meat packing companies. These packages are generally produced using a vertical form fill seal (VFFS) process and equipment, in which a tube is formed from a flat web of roll stock. The tube is formed vertically and longitudinally sealed which may include the use of a vertical sealing bar. The longitudinal seal is formed by heat-sealing the overlapping edges of the packaging film as it passes through a sealing device of the VFFS equipment. The heat-sealing process may be accomplished using supersonic sealing, high frequency sealing and a hot-air knife sealing system. Sealing thermoplastic materials by means of a hot-air knife sealing system typically includes supplying a compressed jet of hot air at temperatures of between 120 and 700° C. and at pressures of between 0.4 and 0.8 bar directed towards the zone where the seal is to be formed between the edges of thermoplastic material. The vertical sealing bar then engages the packaging film for a predetermined dwell time to weld the overlapping edges of the packaging film and form a heat seal. A packaging film must have sufficient heat resistance to withstand relatively high temperatures and pressures during sealing process yet can fuse together to produce a reliable, hermetic heat seal. For this reason, packaging films suitable for use with hot-air knife sealing systems are typically non-heat shrinkable films.
With the longitudinally seal formed, the bottom of the tube may then be sealed with a metal clip applied to the bottom of the tube (known as crimping) and a comminuted product pumped into the open end of the tube. The top of the filled tube is then sealed with another metal clip to produce the final chub package. In appearance, these chubs resemble semi-rigid tubes with the tubular web forming a skin tight layer around the food product. Package sizes may range from 1 to 20 pounds, depending on the intended mode of distribution. The equipment typically used to stuff a food and non-food products into the tubular web can produce stress on the entire package, particularly at the crimped ends and along the longitudinal seal of the tube. During the crimping operation, a sharp-edged leg of the metal clip may pierce or tear the packaging web. As a result, the contents of the package leaks through the hole in the packaging web due to the residual pressure in the package produced during the stuffing process. Consequentially, the package product must then be discarded by the manufacturer. Known chub packages will typically include a strong factory heat seal to prevent the longitudinal seam from pulling apart during the stuffing operation, or during the handling and transport of the packaged article. Although a strong heat seal provides protection against unwanted seal failure, it also makes it difficult for the end user to open the package. Accordingly, there is needed an improved chub packaging web having sufficient heat resistance, toughness and/or penetration resistance to withstand the heat-sealing and crimping operations, and which includes a longitudinal seal of sufficient seal strength to survive the stuffing process and handling, yet can be readily opened by application of manual force without requiring use of a knife or cutting implement.